Invasive medical devices including magnetic region and systems and methods

ABSTRACT

Devices, systems, and methods are described including an invasive medical device with a magnetic region. The magnetic region can include a discontinuity in the magnetic region providing a diameter transition, a plurality of spaced magnetic regions can be provided or the magnetic regions can be encoded with data. Systems and methods are described that include ways to read the data.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation Ser. No. 15/170,531, filed onJun. 1, 2016, the entire content of which is incorporated herein byreference.

FIELD

Principles and embodiments of the present disclosure relate generally todevices including a magnetic region and systems and methods utilizingsuch devices.

BACKGROUND

Traditionally, penetration of an invasive medical device such as aneedle and catheter tubing through skin tissue to reach the vein duringcatheter insertion is invisible to clinicians. For this reason, theymust rely on their first-hand experience with needle insertion incombination with tactile sense to successfully identify the location ofthe vein. This may be a difficult task when attempting to access a smallvein in a deep location under the skin, increasing risk of excess painand/or injury to the patient. There are similar problems with insertionof other invasive medical devices such as guidewires, catheterintroducers and stylets with respect to the inability to preciselyvisualize the location of the invasive medical device.

Emerging procedural guidance systems utilize a combination of ultrasoundand magnetic technologies to provide visualization of subdermal anatomyand device position in the in-plane and out-of-plane orientations. Thiscombination of ultrasound and magnetic methods also allows for theprojection or anticipation of the insertion device position relative tothe patient's anatomy, and thereby improves the likelihood ofsuccessfully accessing the vascular and completing the invasiveprocedure.

One leading technology targets the a portion of the device that isinserted into the patient, e.g., the needle cannula, as the portion ofthe invasive device for magnetization, while another leading technologyuses a permanent magnet located on the hub (e.g., needle hub) of thedevice. Although a permanent magnet offers a more reliable magneticfield as it is not subject to the variation of the clinician magnetizingthe needle at the point of use, it does rely more on a calculatedprojection of the needle tip location. The system that relies onmagnetizing the cannula prior to insertion can more reliably measure theactual tip location, but this method is subject to variability onconsistently magnetizing the cannula as it relies on the clinician toplace the needle into a magnetic device to magnetize the needle.Furthermore current needle guidance systems typically utilize a magneticfield generated by magnetizing the needle by burying the needle into themagnetizer until the point of the needle hits a rubber stopping surface.Damage can occur that is not apparent to the user that can negativelyaffect the insertion process.

In addition, both of these systems utilize a magnetic field generated bya portion of the cannula sub-assembly, and therefore, the system is notable to measure or predict relative motion between the needle hub andcatheter adapter sub-assemblies. Understanding the relative position andmotion of these two sub-assemblies can be used to inform a clinician ofprocedurally important states of the insertion process, such as when theneedle tip reaches the vein, when the catheter tip reaches the vein,when the catheter is advanced to cover the needle tip (“hooding thecatheter”) and thereby safe for further advancement.

It would be desirable to provide medical devices, system and methodsthat could be used with devices, systems and methods to provide improvedvisualization during penetration of a needle through a patient's skintissue.

SUMMARY

Various embodiments are listed below. It will be understood that theembodiments listed below may be combined not only as listed below, butin other suitable combinations in accordance with the scope of thedisclosure.

A first aspect of the disclosure pertains to an invasive medical devicefor insertion into a patient, the device comprising an elongate shafthaving a diameter, an outer surface, a distal tip, and a proximal end,the diameter of the elongate shaft sized to be inserted within anintravenous catheter, at least a portion of the elongate shaft having afirst magnetic region and a discontinuity in the first magnetic regionproviding a diameter transition such that the shaft includes anincreased diameter region.

A second aspect pertains to an invasive medical device for insertioninto a patient, the device comprising an elongate shaft having adiameter, an outer surface, a distal tip, and a proximal end, thediameter of the elongate shaft sized to be inserted within anintravenous catheter, at least a portion of the elongate shaft having afirst magnetic region having a first magnetic field B1 and length L1 andspaced at a distance d from a second magnetic region having a secondmagnetic field B2 and second length L2, wherein L1 and L2 are not equal.

A third aspect pertains to an invasive medical device for insertion intoa patient, the device comprising an elongate shaft having a diameter, anouter surface, a distal tip, and a proximal end, the diameter of theelongate shaft sized to be inserted within an intravenous catheter, atleast a portion of the elongate shaft having a first magnetic regionhaving a first magnetic field B1 and a first length L1 and spaced at adistance d from a second magnetic region having a second magnetic fieldB2 and a second length L2, wherein the first magnetic region is adjacentthe distal tip. In one embodiment of the third aspect the device has atleast a third magnetic region spaced proximally from the second magneticregion, the third magnetic region having a third magnetic field B3 andlength L3. In an embodiment, of the third aspect, the first magneticregion and the second magnetic region are encoded with data. In anembodiment of the third aspect, the data includes information about theinvasive medical device, the information including one or more ofdiameter, length and type of device.

A fourth aspect pertains to a system for determining relative positionof a needle comprising the invasive medical device described herein andmagnetometers positioned with respect to the first magnetic region, andthe second magnetic region. A fifth aspect pertains to a methodobtaining information about an invasive medical device having a distaltip, the method comprising encoding magnetic data on an invasive medicaldevice with a plurality of magnetic fields, the medical device selecteda guidewire, a catheter introducer, a stylet and a hypodermic needle;and reading the data encoded on the invasive medical device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a catheter assembly that can be utilizedaccording to an embodiment;

FIG. 2 is an exploded perspective view of the catheter assembly shown inFIG. 1 ;

FIG. 3 is a top plan view of the catheter assembly shown in FIG. 1 ;

FIG. 4 is a top plan view of a top plan view of an intravenous catheterand an invasive medical device;

FIG. 5 shows the catheter assembly of with the needle subassembly andcatheter adapter subassembly separated;

FIG. 6 is a side view of a needle including a notch according anembodiment;

FIG. 7 is a side view of a needle including a magnetic region accordingan embodiment;

FIG. 8 is a side view of a needle including two magnetic regionsaccording an embodiment;

FIG. 9 a side view of a needle including a magnetic adhesive accordingan embodiment;

FIG. 10 a side view of a needle a spot weld according an embodiment;

FIG. 11 a side view of a needle including a two magnetic regionsaccording an embodiment;

FIG. 12 a side view of a needle including four magnetic regionsaccording an embodiment;

FIG. 13 shows an embodiment of a system including a needle with multiplemagnetic regions; and

FIG. 14 shows an embodiment of a system including a catheter assemblyand a needle according to an embodiment.

DETAILED DESCRIPTION

Before describing several exemplary embodiments, it is to be understoodthat the disclosure is not limited to the details of construction orprocess steps set forth in the following description. The disclosure iscapable of other embodiments and of being practiced or being carried outin various ways.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “various embodiments,” “one or more embodiments” or “anembodiment” means that a particular feature, structure, material, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrases such as“in one or more embodiments,” “in certain embodiments,” “in variousembodiments,” “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily referring tothe same embodiment. Furthermore, the particular features, structures,materials, or characteristics may be combined in any suitable manner inone or more embodiments.

Reference will now be made to figures wherein like structures will beprovided with like reference designations. It is understood that thedrawings are diagrammatic and schematic representations of exemplaryembodiments, and are neither limiting nor necessarily drawn to scale.The present disclosure relates to medical devices, systems and methodsfor enhancing visualization of an invasive procedure requiringprocedural guidance, such as providing enhanced visualization of avascular access device during an invasive insertion procedure. In oneembodiment, a magnetic feature is placed on the invasive medical device,for example, on a needle, which allows the magnetic feature to be placedcloser to the tip, thus increasing the precision of the placementguidance. Embodiments of the disclosure pertain to an invasive medicaldevice with a shaft, a least a portion of which have a magnetic region.The magnetic region can be provided in a variety of ways, including alayer ferromagnetic metal, a layer of paramagnetic metal, a spot weld ofmagnetic metal, a ferrule and combinations thereof. In otherembodiments, the magnetic region can be provided by changing thecomposition of the region to increase the magnetic susceptibility of theregion, or the magnetic region can be provided by cold working theinvasive medical device. In specific embodiments, there is adiscontinuity in the magnetic region. In other embodiments, the shafthas at least two magnetic regions. In one or more embodiments, themagnetic regions are encoded with data. The medical devices describedherein can be used in various systems and methods described furtherbelow.

In one or more embodiments, the invasive medical devices are part of acatheter adapter including a needle subassembly that can be used and acatheter adapter subassembly. In an embodiment the catheter adaptersubassembly includes either a permanent magnet element or magnetizablefeature.

It is to be understood that the word “proximal” refers to a directionrelatively closer to a clinician using the device to be describedherein, while the word “distal” refers to a direction relatively furtherfrom the clinician. For example, the end of a needle placed within thebody of a patient is considered a distal end of the needle, while theneedle end remaining outside the body is a proximal end of the needle.“Magnetic feature” refers to a feature that includes a permanent magnetand/or a magnetizable material that has been magnetized by an externallyapplied magnetic field such that the magnetic feature can be detected byan ultrasound system. A “magnetizable feature” refers to an element thatcan become magnetized and is detectable by an ultrasound system asdescribed further herein. “Invasive medical device” refers to devicesthat are inserted into the vasculature of a patient such as a needle, aguidewire, a catheter introducer and a stylet. In specific embodiments,“invasive medical device” refers to a medical device that is sized andshaped to be inserted into an intravenous catheter.

Referring now to FIGS. 1-3 , an exemplary embodiment of a catheterassembly 10 is shown, including a catheter adapter subassembly 12 and aneedle subassembly 14. The catheter adapter subassembly 12 comprises acatheter adapter 16, catheter tubing 18 and a securement element 22, andthe needle subassembly 14 further includes a needle 20, connected to aneedle hub 24, at a hub distal end 23 and a vent plug 26. In otherembodiments not shown, the needle 20 can be retracted into the needlehub 24 after the needle 20 has been used to prevent accidental needlesticks of a patient or a clinician. While the embodiments of invasivemedical devices described in this disclosure primarily are directed toneedles, it will be understood that the invasive medical device can alsobe in the form of a wire, which may be in the form of a guidewire, acatheter introducer or a stylet. As used herein, “stylet” refers to awire run through a catheter or cannula to render it stiff or to removedebris from its lumen. A “catheter introducer” refers to wire used tofacilitate insertion of an intravenous catheter. A “guidewire” is a wirethat can be used to guide a catheter into place during venous catheterand other bodily catheter insertions. In venous insertions, the purposeof a guidewire is to gain access to the blood vessels using a minimallyinvasive technique. FIG. 4 depicts a wire 50, which may be in the formof a catheter introducer, stylet or guidewire, which is sized and shapedto be inserted into an intravenous catheter 68. The guidewire, stylet orcatheter introducer has an elongate shaft 52 and a distal tip 54 thatcan be inserted into the intravenous catheter 68.

Referring now to FIG. 5 , an embodiment of a needle subassembly 121 isshown including a needle 120 having a cannula 122 defining an elongateshaft 126 having a proximal end 120 and a distal tip 123. The proximalend 120 is connected to a needle hub 124 at hub distal end 125.

FIG. 6 is enlarged view of a needle a needle 220 having a cannula 222defining an elongate shaft 226 having a proximal end 221 and a distaltip 223. The needle 220 is sized and shaped for insertion into thevasculature of a patient, which may be through an intravenous catheter.The shaft 226 of the needle 220 defines and outer surface 228 and anouter diameter “D”. In the embodiment shown, at least a portion of theelongate shaft 226 includes at least a first magnetic region 230, asecond magnetic region 232 and a third magnetic region 233, which arespaced laterally along the shaft 226 of the needle 220. As shown in FIG.6 , the second magnetic region 232 is spaced proximally along the shaft226 from the first magnetic region 230, and the third magnetic region233 is spaced proximally along the shaft 226 from the second magneticregion 232. In the embodiment shown, there is a discontinuity 235 in thearea of the second magnetic region 232. As shown in FIG. 6 , the outerdiameter of the needle 220 at the discontinuity 235 is less than theouter diameter “D” at the remainder of the needle 220. It will beunderstood that that the discontinuity 235 can have an outer diameterthat is larger than the outer diameter “D” at the remainder of theneedle 220. In either case, the shaft 226 includes an increased ordecreased diameter region as a result of the discontinuity 235. In theembodiment shown in FIG. 6 , the discontinuity 235 is in the form of anotch 237. The notch 237 is shown as being generally rectangular inshape, however, it will be understood that the notch 237 could be avariety of shapes, including triangular, oval, round, parabolic orirregularly shaped by crimping or other techniques to reduce thediameter at the notch 237. A magnet or magnetic element can be disposedin the notch 237. The first magnetic region 230 has a first magneticfield strength B1, the second magnetic region 232 has a second magneticfield strength B2, and the third magnetic region 233 has a thirdmagnetic field strength B3. In one embodiment, the magnetic fieldstrengths B1, B2 and B3 are equal. In another embodiment each of themagnetic field strengths B1, B2 and B3 are not equal. Magnetic fieldstrength can be used measured using a variety of different technologies,including gaussmeters and magnetometers.

According to one or more alternative embodiments, the discontinuityalong the shaft of the needle can be in various forms, for example, alayer ferromagnetic metal, a layer of paramagnetic metal, a spot weld ofmagnetic metal, a ferrule and combinations thereof. According to one ormore embodiments, the needle shaft can be slidably disposed withincatheter tubing, for example, as shown in FIG. 3 , where needle 20 isinserted within catheter tubing 18, as a catheter assembly 10 thatincludes a catheter adapter subassembly 12 and a needle subassembly 14.

FIG. 7 is enlarged view of a needle a needle 320 having a cannula 322defining an elongate shaft 326 having a proximal end 321 and a distaltip 323. The needle 320 is sized and shaped for insertion into thevasculature of a patient, which may be through an intravenous catheter.The shaft 326 of the needle 320 defines and outer surface 328 and anouter diameter “D”. First magnetic region 330 includes a discontinuity335, which is provided by a magnetic ferrule 337. The outer diameter ofthe needle 320 at the discontinuity 335 is greater than the outerdiameter “D” at the remainder of the needle 320. The magnetic region 330has an increased outside diameter at the discontinuity 335 provided bythe ferrule.

FIG. 8 shows an embodiment similar to FIG. 7 , and further includes asecond discontinuity 336 having an outer diameter that is greater thanthe diameter D of the shaft 326. The second discontinuity is provided bya second ferrule 339.

FIG. 9 shows an embodiment in which the discontinuity 335 is provided bya magnetic adhesive 341 on the outer surface 328 of the shaft 326, whichprovides a discontinuity 335 such that the outer diameter at thediscontinuity 335 is greater than the outer diameter D of the shaft 326.According to one or more embodiments, the magnetic adhesive includes anadditive selected from a paramagnetic additive, a ferromagnetic additiveand combinations thereof. The adhesive additive according to one or moreembodiments includes a component selected from the group consisting ofpowdered iron, magnetic iron oxide, magnetic titanium oxide, magneticpowdered steel, and a magnetic iron alloy, and mixtures thereof. In oneor more embodiments, the magnetic iron alloy includes one or more ofnickel, zinc, and copper. In one or more embodiments, the adhesiveadditive further comprises a component selected from chromium,magnesium, molybdenum and combinations thereof. The adhesive can be anysuitable adhesive such as a curable glue containing magnetizablenanoparticles such as magnetizable metal nanoparticles or magnetizablemetal oxide nanoparticles. The magnetizable metal can include iron,cobalt, nickel and alloys of iron, cobalt, and nickel. According to oneor more embodiments, the size of the magnetic nanoparticles is in therange of about 1 nanometer (nm) to about 100 nm. In one embodiment,adhesive is a light-curable glue, and in another embodiment, theadhesive is a heat-curable glue.

FIG. 10 shows an embodiment in which the discontinuity 335 is providedby a spot weld 343 on the outer surface 328 of the shaft 326, whichprovides a discontinuity 335 such that the outer diameter at thediscontinuity 335 is greater than the outer diameter D of the shaft 326.According to one or more embodiments, the spot weld includes an additiveselected from a paramagnetic additive, a ferromagnetic additive andcombinations thereof. The spot weld according to one or more embodimentsincludes a component selected from the group consisting of powderediron, magnetic iron oxide, magnetic titanium oxide, magnetic powderedsteel, and a magnetic iron alloy, and mixtures thereof. In one or moreembodiments, the magnetic iron alloy includes one or more of nickel,zinc, and copper. In one or more embodiments, the spot weld additivefurther comprises a component selected from chromium, magnesium,molybdenum and combinations thereof.

According to one or more embodiments, the shaft has a first magneticregion having a first magnetic field B1 and a second magnetic regionhaving a second magnetic field B2, wherein B1 and B2 are not equal.Alternatively, the first magnetic region has a length L1 and is spacedapart on the shaft at a distance d1 from the second magnetic regionwhich has a length L2 and L1 and L2 are different. In other embodiments,the shaft has a third magnetic region spaced apart at a distance d2 fromthe first region having a third magnetic field B3 and length L3, whereinB2 and B3 are not equal and L2 and L3 are not equal. According to one ormore embodiments, a system is provided in for determining relativeposition of a needle which includes the needle described according toany of the above described embodiments, and magnetometers positionedwith respect to the first magnetic region, the second magnetic regionand the third magnetic region.

FIG. 11 shows another embodiment of the disclosure, in which an invasivemedical device shown in the form of a needle 420 having a cannula 422defining an elongate shaft 426 having a proximal end 421 and a distaltip 423. The needle 420 is sized and shaped for insertion into thevasculature of a patient, which may be through an intravenous catheter.The shaft 426 of the needle 420 defines and outer surface 428 and anouter diameter “D”. First magnetic region 430 has a first magnetic fieldstrength B1 and second magnetic region 431 has a second magnetic fieldstrength B2. The magnetic regions 430 and 431 can be provided asdescribed above with respect to FIGS. 4-10 , or alternatively, themagnetic regions can be provided by cold working the shaft 426 of theneedle 420, or modifying the composition of the needle 420 to increasethe strength of the magnetic field B1 and B2. In the embodiment shown inFIG. 11 , the outer diameter “D” of the shaft 426 may be constant alongthe length of the needle. Alternatively, there may be a diametertransition at the first magnetic region 430 and/or the second magneticregion 431 such that the outer diameter in the first magnetic region 430and/or the second magnetic region 431 is larger than the outer diameterof the shaft 426. In other embodiments, there may be a diametertransition at the first magnetic region 430 and/or the second magneticregion 431 such that the outer diameter in the first magnetic region 430and/or the second magnetic region 431 is smaller than the outer diameterof the shaft 426. The magnetic regions 430 and 431 are shown as beingadjacent to each other. In alternative embodiments, the magnetic regions430 and 431 may be spaced apart. In the embodiment shown, at least oneof the magnetic regions 430, 431 is adjacent the distal tip 423.

FIG. 12 shows another embodiment in which an invasive medical deviceshown in the form of a needle 520 having a cannula 522 defining anelongate shaft 526 having a proximal end 521 and a distal tip 523. Theneedle 520 is sized and shaped for insertion into the vasculature of apatient, which may be through an intravenous catheter. The shaft 526 ofthe needle 520 defines and outer surface 528 and an outer diameter “D”.First magnetic region 530 has a first magnetic field strength B1, secondmagnetic region 531 has a second magnetic field strength B2, thirdmagnetic region 532 has a third magnetic field strength B3, and fourthmagnetic region 533 has a fourth magnetic field strength B4 The magneticregions 530, 531, 532, and 533 can be provided as described above withrespect to FIGS. 4-10 , or alternatively, the magnetic regions can beprovided by cold working the shaft 526 of the needle 520, or modifyingthe composition of the needle 520 to increase the strength of themagnetic fields B1, B2, B3, and B4. In the embodiment shown in FIG. 12 ,the outer diameter “D” of the shaft 526 may be constant along the lengthof the needle. Alternatively, there may be a diameter transition at thefirst magnetic region 530 and/or the second magnetic region 531, thirdmagnetic region 532 and fourth magnetic region 533 such that the outerdiameter in the first magnetic region 530 and/or the second magneticregion 531, and/or third magnetic region 532 and/or fourth magneticregion 533 is larger than the outer diameter of the shaft 526. In otherembodiments, there may be a diameter transition at the first magneticregion 530 and/or the second magnetic region 531, and/or third magneticregion 532, and/or fourth magnetic region 533 such that the outerdiameter in the first magnetic region 530 and/or the second magneticregion 531, third magnetic region 532 and/or fourth magnetic region 533is smaller than the outer diameter of the shaft 526.

It will be understood that while FIG. 12 shows four magnetic regions531, 532, 533, and 533, the disclosure and claims are not limited to aparticular number of magnetic regions. For example, an invasive medicaldevice can have an elongate shaft having one, two, three, four, five,six, seven, eight, nine, ten, or more magnetic regions spaced adjacentto one another or spaced apart along the elongate shaft. As shown inFIG. 11 , the second magnetic region 531 is located proximally to thefirst magnetic region 530, and the third magnetic region 532 is locatedproximally to the second magnetic region 531 and the fourth magneticregion 533 is located proximally to the third magnetic region 532. Inother embodiments, these regions can be proximally spaced.

By providing multiple magnetic regions on the invasive medical deviceshaft, which can be placed in proximity to the distal tip, a higherdegree of precision of device placement guidance can be achieved. Inaddition, a medical device having a plurality of magnetic regionsenables a wide variety and large amount of data to be encoded to or froma magnetic signature on the needle provided by the multiple magneticregions. Furthermore, invasive medical devices that use only onemagnetic marker or region near the tip of the needle, which can have avariety of issues as the single region moves further distances from thesensor as the invasive device is advanced further into the body during aprocedure. According to one or more embodiments, a device of the typeshown in FIG. 12 having multiple magnetic regions or markers can improveprocedural guidance in deep insertions into deeper veins. Multiplemagnetic regions proximally adjacent or spaced along the axis of theshaft of the invasive medical device extend the limit of the sensor fordeeply inserted device and catheter tips. This allows the sensor (e.g.,a magnetometer of an ultrasound system) to continue tracking themagnetic regions located proximally away from the distal end of themedical device, and precisely track the distal tip location for verydeep insertions/placements.

Multiple magnetic regions enable the invasive medical device to beencoded with multiple magnetic signatures that will provide proceduralguidance systems with greater resolution and precision in locating theneedle position. According to one or more embodiments, a system can beprovided such that a sensor head can read patterns of magneticsignatures that are written and/or recorded onto the invasive medicaldevice shaft. This technique is analogous to a rotational disk driveused for a computer memory, where patterns of magnetic signatures arerecorded onto a magnetic substrate using current from a read/write head,and then the data is read back when required. Thus, according to one ormore embodiments, an invasive medical device is provided, for example, aneedle, a catheter introducer or a stylet contains a plurality ofmagnetic regions on the shaft of the invasive medical device, and aread/write head using current records patterns of magnetic signatures toencode information into the invasive medical device. An invasive medicaldevice containing such magnetic signatures encoded onto the deviceprovides a higher level of accuracy when sensing the position of themedical device (e.g., a needle) and can provide information to thesensor head about the device, for example, gauge, outside diameter,size, length, brand, type, etc.

Encoding of information on the shaft of an invasive medical device suchas a needle can be accomplished in several ways. FIG. 13 shows anotherembodiment in which an invasive medical device shown in the form of aneedle 620 having a cannula 622 defining an elongate shaft 626 having aproximal end 621 and a distal tip 623. The shaft 626 of the needle 620defines and outer surface 628 and an outer diameter “D”. First magneticregion 630 has a first magnetic field strength B1, second magneticregion 631 has a second magnetic field strength B2, and third magneticregion 632 has a third magnetic field strength B3. The magnetic regions630, 631, and 632, can be provided as described above with respect toFIGS. 4-12 , or alternatively, the magnetic regions can be provided bycold working the shaft 626 of the needle 620, or modifying thecomposition of the needle 620 to increase the strength of the magneticfields B1, B2, and B3. In the embodiment shown in FIG. 13 , the outerdiameter “D” of the shaft 626 may be constant along the length of theneedle. Alternatively, there may be a diameter transition at the firstmagnetic region 630 and/or the second magnetic region 631, and thirdmagnetic region 632 such that the outer diameter in the first magneticregion 630 and/or the second magnetic region 631, and/or third magneticregion 532 is larger than the outer diameter of the shaft 626. Accordingto one or more embodiments, the magnetic regions shown in FIG. 13 areprepared by insulating and coating the shaft with a magnetic layer. Thenthe shaft of the device can be “written” with a signature indicating thetype of device, gauge, geometry of the distal tip, and length by varyingthe length and/or field strength of the magnetic regions 630, 631, 632.Alternatively a distance d1 and d2 between the magnetic regions 630, 631and 631 and where the magnetic regions switch polarity can provide theencoding to enable storage of a large amount of information.Furthermore, the length of each magnetic region L1 for magnetic region630, L2 for magnetic region 631 and L3 for magnetic region 633 can bevaried to provide a way of encoding information. Thus, an encodingscheme can be developed that uses one or more features of magneticregions 630, 631 and 632 to encode information regarding the 620. Forexample, a combination of the lengths L1, L2 and L3 together with thespacings d1 and d2 can be used to device a code or signature to provideinformation about the needle 620 such as the needle length, needlegauge, type of needle or other information about the needle 620.Furthermore, each magnetic region 630, 631 and 632 is shown as having apole orientation of +/− from the distal toward the proximal end. In oneor more embodiments, the pole orientations can be varied to provide anadditional way to encode needle information. Thus, while magneticregions 630, 631 and 632 are shown as having pole orientations of +/−,+/− and +/−, these pole orientations can be varied in any number of wayssuch as +/−, −/+ and +/−, or alternatively, −/+, +/− and −/+. Thus, bychanging pole orientation of the magnetic regions, another variable ofthe magnetic regions can be utilized to provide another way to encodeneedle information. A detector head 670 containing a plurality of spacedsensors 672, 673 and 674 (for example, magnetometers) can be used todetect magnetic field strength, length and spacing of the magneticregions. The detector head 670 can be in wired or wireless communicationwith a processor 675 adapted to determine process data from theinformation encoded on the shaft of the medical device and/or datapertaining to the detected field the position and orientation of themagnetic regions relative to the detector head 670. This magneticallydetected position can then displayed on a display 678 together with theultrasound image. The processor 675 can be in communication with amemory 677 that stores the encoded information pertaining to the needle620. The processor can access or look up encoded information stored onthe memory to obtain information about the needle.

The detector head 670 can be connected by a wireless connection to abase unit 680 which is in wireless or wired (e.g. USB) communicationwith the processor 675 and the display 678. The base unit 680 can beintegrated with, or some of its functions performed by, the processor675 or the detector head 670. The base unit 680 receives measurementsfrom detector head 670 and calculates the position, or optionally theposition and orientation, of magnetic regions. The base unit 680 canalso receive additional information such as the state of charge of themagnetometric detector's battery and information can be sent from thebase unit 680 to the detector head 670, such as configurationinformation. The base unit 680 forwards the results of its calculations,i.e. the position and, optionally, orientation, to the processor 675 forinclusion in the displayed ultrasound image of an image of the invasivedevice, for example, the needle 620.

It will be appreciated that FIG. 13 is not drawn to scale or density ofthe encoding, but representative in the fact that the detector head andthe encoding can be optimized for the correct amount of signalresolution and information desired to be conveyed.

Thus, FIG. 13 illustrates a system for determining relative position ofan invasive medical device such as a needle, as magnetometers positionedwith respect to the one or more magnetic regions on the shaft of themedical device. In one or more embodiments, the needle shown in FIG. 13can be part of a needle subassembly further including a needle hubmounted to the proximal end of the needle, and the needle subassemblycan be part of a catheter assembly as shown in FIGS. 1-3 , and includeintravenous catheter tubing as part of a catheter adapter subassembly.The catheter adapter subassembly can include magnetic feature, such as amagnetizable feature magnetizable by an applied magnetic field or apermanent magnet. The magnetizable feature on the catheter adapter canbe a conical metal mandrel for connecting the catheter tubing to the hubcatheter or tubing adhesive which can be any suitable adhesive such as acurable glue containing magnetizable nanoparticles such as magnetizablemetal nanoparticles or magnetizable metal oxide nanoparticles. Themagnetizable metal can include iron, cobalt, nickel and alloys of iron,cobalt, and nickel. According to one or more embodiments, the size ofthe magnetic nanoparticles is in the range of about 1 nanometer (nm) toabout 100 nm. In one embodiment, adhesive is a light-curable glue, andin another embodiment, the adhesive is a heat-curable glue. In otherembodiments, a blood control component of the catheter adaptersubassembly provides the magnetizable feature. According to one or moreembodiments, the blood control component is made from martensitic orferritic stainless steels, for example, type 420 or type 430 stainlesssteel. The blood control component (metal spring for instance) or theneedle tip safety clip or v-clip that moves with the catheter adapteruntil fully advanced. In one or more embodiments, the magnetic featureon the catheter adapter subassembly includes a magnetic wedge on thecatheter adapter body.

In one or more embodiments, the catheter adapter subassembly includesthe magnetizable feature, wherein the magnetizable feature includesmagnetizable catheter tubing. In one or more embodiments, at least aportion of the polyurethane tubing comprises a magnetizable compositionwhich is magnetizable by an externally applied magnetic field, themagnetizable composition comprising a magnetic material dispersed in thepolyurethane. In certain embodiments, the magnetic composition isdispersed in the polymeric material, for example, polyurethane, whichforms the tubing. In a specific embodiment, the magnetizable compositioncomprises an inner layer surrounding the lumen of the catheter with anouter layer of non-magnetizable polymeric material, for example,polyurethane. In an alternative specific embodiment, the layer ofmagnetizable composition is an outer layer surrounding an inner layer ofnon-magnetizable polyurethane. In one or more embodiments, themagnetizable composition forms longitudinal segments of the catheterseparated by longitudinal segments of non-magnetizable polymericmaterial, for example, polyurethane.

In any of the foregoing embodiments of the catheter, the magnetizablecomposition may further comprise a radiopaque component. Alternatively,in any of the foregoing embodiments, a non-magnetizable portion ofcatheter may comprise a radiopaque component.

The magnetometers of the system can include three differentmagnetometers arranged in a three-dimensional grid array as part of anultrasound system which can derive a three-dimensional correlation toobtain a distance from the grid array to at least one of the firstmagnetic field, the second magnetic field and the third magnetic field.In one or more embodiments, the three-dimensional correlation isdetermined by a function I=f(B_(i) μ_(r)), where i=x or y or z alongthree axes, x, y and z are distances in three planes, B is a knownmagnetic field produced by the first magnetic field, the second magneticfield and the third magnetic field. A system including a magneticfeature on the catheter adapter subassembly and the needle subassemblycan be used to determine relative motion of the needle and the catheteradapter subassembly as the needle is disposed within intravenouscatheter tubing and they are slidably moved with respect to each other.

Another aspect of the disclosure pertains to a method obtaininginformation about an invasive medical device, which includes encodingmagnetic data on an invasive medical device with a plurality of magneticfields, the medical device selected a guidewire, a catheter introducer,a stylet and a hypodermic needle; and reading the data encoded on theinvasive medical device. The reading can be accomplished as describedabove, using an ultrasound head with a plurality of magnetometers. Thedata can include at least one of diameter of the medical device, lengthof the medical device and type of the medical device. In one or moreembodiments, a method can include encoding the shaft of an invasivemedical device such as a guidewire, a catheter introducer, a stylet anda needle, and encoding is accomplished by correlating information withrespect to length and/or spacing of a plurality of magnetic fieldsadjacent to each other or spaced apart on the shaft of the medicaldevice. In one or more embodiments, reading data from the medical deviceincludes reading position of the magnetic fields with respect to thedistal tip of the needle. Reading the data in one or more embodimentsutilizes a three-dimensional array of magnetometers as part of anultrasound system, and the ultrasound system derives a three-dimensionalcorrelation to obtain a distance from the array of magnetometers to atleast one of the magnetic fields. In one or more embodiments of themethod, the three-dimensional correlation is determined by the functionI=f(B_(i) μ_(r)), where i=x or y or z along three axes, x, y and z aredistances in three planes, B is a known magnetic field produced by theat least one of the magnetic fields

A second way of encoding the shaft of an invasive medical device wouldbe to replicate the magnetic feature (ferrule, drop of magneticadhesive, spot weld, etc. at intervals along the shaft. The distancebetween the magnetic regions could be encoded to give the type, gaugeand length of the product used, In addition, the plurality of magneticregions can be used for visualization of the device during an insertionprocedure.

The magnetic regions according to any of the embodiments described abovecan be provided in a variety of ways, in addition to those specificallydiscussed. A common material used to make invasive medical devices suchas needles, stylets and introducers includes stainless steel, namelytype 304 or type 316 stainless steel. There are five classes ofstainless steel, namely, ferritic (e.g., types 405, 430, 442),austenitic (e.g., types 201, 301, 302, 303, 304, 316), martensitic(e.g., types 403, 410, 416), duplex (e.g., types 2205, Alloy 255), andprecipitate-hardened (e.g., types 17-4PH, PH 17-7) and generally, onlyaustenitic stainless steel is nonmagnetic. The first four classes aredefined based on the microstructure of the metal with the last class,precipitate-hardened, based on its heat treatment. Microstructureprovides the stainless steel its magnetic properties.

However, while austenitic stainless steel is not magnetic, it can bemagnetic by modifying the material in a number of ways. For example, aportion of the microstructure can be changed to any one of the otherfour classes listed above so that the material would have some magneticpermeability, i.e. magnetism, built into the material. Themicrostructure of austenitic stainless steel can be changed by a processcalled martensitic stress induced transformation. This is amicrostructural change from austenite to martensite, and thetransformation can occur due to cold working as well as slow coolingfrom austenitizing temperatures. After cold working or slow cooling anaustenitic stainless steel will have an appreciable level of martensiticmicrostructure. Due to martensite being magnetic, the once nonmagneticaustenitic stainless steel will now have a degree of magnetism.

Low alloy content stainless steel (particularly that of low nickel,carbon, and/or nitrogen) are more susceptible to martensitic stressinduced transformation than stainless steel with higher alloyingelements. Type 304 is an example of a stainless steel that is quitesusceptible to forming martensite after cold working.

The austenite in the alloy transforms into martensite at high degrees ofcold working relative to the tempered state. Typically thesusceptibility could increase from ˜100 ppm to 10,000 ppm when annealedstainless steel is cold worked to full hardness. To increase thesusceptibility, additional cold working of the needle shaft to induce ahigher amount of martensite in the alloy, needles may be spring temperedto maximize the mechanical properties after cold working. Additionallythe needle may be heat-treated to remove excess martensite and controlthe exact amount of desired susceptibility.

According to one or more embodiments, to increase the magnetization ofthe material used to make the invasive medical device, the alloycomposition of the needle could be enhanced by adding ferromagneticmetal to the alloy. For example, type 304 stainless steel typicallycontains 18% Cr by weight and 8% Ni by weight with a max of 2% Mn byweight. In an embodiment, to provide a stainless steel with highermagnetic susceptibility, cobalt could be added to this alloy inquantities ranging from 0.01% to 5% by weight, and/or the manganesecontent could be increased from the maximum allowable 2% to 3%, 4% or 5%by weight. Additionally, rare-earth metals such as gadolinium orneodymium could be added in small quantities<5% by weight to furtherenhance magnetic susceptibility of the alloy. Any of these materials canbe used in the region of the discontinuity described above, whether byadding a layer of material, a ferrule, a crimp or a spot weld.

In one or more embodiments, magnetic susceptibility could also beenhanced by adding layers of a ferromagnetic metal to the shaft of theinvasive medical device. In an exemplary embodiment, a needle having anouter diameter of approximately 0.5-1.5 mm can also have a plating ofnickel deposited by electroplating or electroless plating methods inthicknesses ranging from 0.1 microns to 100 microns to increase magneticsusceptibility of the magnetic region or regions. In alternativeembodiments, layers of other metals could be applied to improve specificproperties, such as a layer of Cr or CrO₂ on the outside to preventcorrosion, or an intermediate layer of Co or Neodymium to increasemagnetic susceptibility.

Other examples include adding a coaxial layer of a ferromagneticmaterial such as iron within the tubing used to make the needle.Additional surface barriers layers can be applied by electroplating orother suitable techniques to machined or ground surfaces where apotentially toxic metal like Co or Fe would be otherwise exposed.

Magnetic tip location sensing can also be improved according to one ormore embodiments by placing a magnetic region closer to one end of theneedle, preferably the sharp distal tip of the needle. If the magneticregion is placed at a known location at a fixed distance from the tip ofthe needle, then arrays of magnetometers as can be used to measure themagnetic field strength variation from the magnetic region and locatethe distal tip of the needle. According to one or more embodiments thatinclude a ferrule, the ferrule may also serve other functions such asneedle stick injury prevention. The ferrule may be made of a material ofhigher or lower magnetic susceptibility than the rest of the needle andmay be attached by spot welding to the needle. Alternatively, a spotweld of material may be deposited over the needle surface by welding iton and such a spot may also serve a another function in a needle stickinjury prevention feature.

In embodiments that include magnetic adhesive, according to one or moreembodiments, the adhesive is applied to the needle shaft, and is locatedunder the catheter when the needle is inserted into the catheter tubing,and thus the patient will not perceive or sense the presence of theadhesive. According to one or more embodiments, the magnetic adhesiveprovide the magnetic region on the device to enable detection of theneedle and provide guidance the visualization system requires, and theadhesive could also be used prevent the needle from passing through asafety washer in systems that include safety washer.

Another aspect of the disclosure pertains to a system for determiningcatheter tip location when the catheter tubing is inserted in a patient.According to one or more embodiments, a system provides a way toindependently measure the cannula tubing tip location by measuring thelocation and vector of the permanent magnet, and calculating andpredicting the catheter tip location relative to the position of themagnetic sensor(s) on an ultrasound probe and the ultrasound informationtransmitted from the sensors on the ultrasound probe. A permanent magneton a device with north and south poles on axis with the catheter andneedle and a known geometrical relationship to one or more featuresfixed on the catheter assembly provides a measurement datum that ismeasureable by the ultrasound probe magnetic sensors. From themeasurement datum based on the one or more features on the catheterassembly, the direction vector and position of the catheter tip or otherfeatures can be calculated. A magnetized magnetizable needle or featureon the needle can then be used to independently measure the position ofthe needle tip. The measured position of the needle tip or feature onthe needle can then be compared relative to the calculated position ofthe catheter tip to provide more specific information related to thecatheter placement process, such as needle and catheter tip positionrelative to the patient's anatomy. This information can be used todetermine (a) if the catheter is properly seated and ready for insertion(i.e., no over the bevel condition), (b) when the needle tip is in the“hooded” position (needle tip just inside of the catheter tip), and (c)and (d) when the catheter is advanced to specific distances and atangles suggesting successful placement in the vein.

FIG. 14 shows an ultrasound system 700 including a catheter adaptersubassembly 712 comprising a magnetizable feature 732 that has beenmagnetized as described herein is shown inside of a patient's body 800.A magnetometric detector 711 comprising an array of magnetometers 720(which can be housed in a probe of an ultrasound system, not shown)arranged in a 3-D array can be used to sense the magnetic field 714together with the terrestrial magnetic field and any other backgroundmagnetic field. The magnetometric detector 711 is in communication withan ultrasound processor 730 adapted to determine from the detected fieldthe position and orientation of the magnetizable feature 732 relative tothe magnetometric detector 711. This magnetically detected position isthen displayed on a display 750 together with the ultrasound image.

The ultrasound system 700 can be a two dimensional B-mode ultrasoundsystem with an ultrasound probe modified by the provision of themagnetometric detector 711. The ultrasound processor 730, which can beconnected to the ultrasound probe via a cable 735, sends electricalsignals to the magnetometric detector 711 to cause it to generateultrasound pulses and interpreting the raw data received from thetransducer probe housing the magnetometric detector 711, whichrepresents echoes from the patient's body, to assemble it into an imageof the patient's tissue.

The magnetometric detector 711 can be attached to the ultrasound probeand can be battery powered or powered from the ultrasound system. Inspecific embodiments, positioning elements are provided on themagnetometric detector 711 to ensure that it is always attached in thesame well-defined position and orientation. The magnetometric detector711 can connected by a wireless connection to a base unit 740 which isin wireless or wired (e.g. USB) communication with the ultrasoundprocessor 730 and the display 750. The base unit 740 can be integratedwith, or some of its functions performed by, the ultrasound processor730 or the magnetometric detector 711.

The base unit 740 receives normalized measurements from magnetometricdetector 711 and calculates the position, or optionally the position andorientation, of magnetizable feature 732. The base unit 740 can alsoreceive additional information such as the state of charge of themagnetometric detector's battery and information can be sent from thebase unit 740 to the magnetometric detector 711, such as configurationinformation. The base unit 740 forwards the results of its calculations,i.e. the position and, optionally, orientation, to the ultrasoundprocessor 730 for inclusion in the displayed ultrasound image of animage of the catheter.

In one or more embodiments, the base unit 740 can be integrated into theultrasound system 700 with the ultrasound processor 730 and themagnetometric detector 711 being in direct communication with theultrasound system 700 either via wireless link or using the samephysical cable 735.

Thus, in one or more embodiments, the magnetizable feature is magnetizedusing any suitable device that can produce an magnetic field tomagnetize a needle or medical device to produce a magnetic field B at adistance x through tissue of permeability μ_(r), and the correlation iscalculated as x=f(B, μ_(r)). In one or more embodiments, threemagnetometers 720 are placed orthogonally to each other are used toderive a 3-dimensional correlation I=f(B_(i), μ_(r)), wherein i=x or yor z along three axes. In a specific embodiment, the distance from themagnetizable feature to the 3-dimensional array of magnetometers iscalculated. In a further specific embodiment, location of the array ofmagnetometers in reference to an ultrasound sensor of an ultrasoundimaging system is used to calculate a location of the magnetizablefeature with respect to the ultrasound sensor. In another specificembodiment, the method comprises displaying an image of the magnetizablefeature.

Although the disclosure herein provided a description with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thedisclosure. It will be apparent to those skilled in the art that variousmodifications and variations can be made to the devices, methods andsystems described in the of the present disclosure without departingfrom the spirit and scope thereof. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A needle assembly comprising: an elongate shafthaving a diameter, an outer surface, a distal tip, and a proximal end,the diameter of the elongate shaft sized to be inserted within anintravenous catheter, at least a portion of the elongate shaft having afirst magnetic region and a discontinuity in the first magnetic regionproviding an increased diameter region relative to the diameter of theelongate shaft, the discontinuity comprising a magnetic adhesive.
 2. Theneedle assembly of claim 1, wherein the needle assembly comprises ahypodermic needle.
 3. The needle assembly of claim 2, wherein the shaftis disposed within intravenous catheter tubing.
 4. The needle assemblyof claim 3, wherein the magnetic adhesive increases the diameter of theshaft of the hypodermic needle.
 5. The needle assembly of claim 3wherein the magnetic adhesive on the outer surface of the shaft of thehypodermic needle.
 6. The needle assembly of claim 5, wherein themagnetic adhesive includes an additive selected from a paramagneticadditive, a ferromagnetic additive and combinations thereof.
 7. Theneedle assembly of claim 6, wherein the additive includes a componentselected from the group consisting of powdered iron, magnetic ironoxide, magnetic titanium oxide, magnetic powdered steel, and a magneticiron alloy, and mixtures thereof.
 8. The needle assembly of claim 7,wherein the magnetic iron alloy includes one or more of nickel, zinc,and copper.
 9. The needle assembly of claim 8, wherein the additivefurther comprises a component selected from chromium, magnesium,molybdenum and combinations thereof.
 10. The needle assembly of claim 3,wherein the hypodermic needle comprises martensitic stainless steel. 11.A system including the needle assembly of claim 3, wherein thehypodermic needle is part of a needle subassembly further including aneedle hub mounted to the proximal end of the hypodermic needle, and thesystem further comprises a catheter adapter assembly.
 12. The system ofclaim 11, the catheter adapter assembly including catheter tubing and acatheter adapter body, wherein the shaft is slidably engaged with theintravenous catheter tubing.
 13. The system of claim 12, wherein thecatheter adapter assembly further comprises a magnetic feature.
 14. Thesystem of claim 13, wherein the magnetic feature comprises a permanentmagnet with north and south poles on axis with the catheter andhypodermic needle and a known geometrical relationship to one or morefeatures fixed on the catheter adapter assembly providing a measurementdatum that is measurable by ultrasound probe magnetic sensors.